[PATCH v3 2/8] lib: add "on" and "off" to strtobool

[Kees Cook <keescook@chromium.org>]

Several places in the kernel expect to use "on" and "off" for their
boolean signifiers, so add them to strtobool.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
 lib/string.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/lib/string.c b/lib/string.c
index 0323c0d5629a..d7550432f91c 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -635,12 +635,16 @@ EXPORT_SYMBOL(sysfs_streq);
  * @s: input string
  * @res: result
  *
- * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
+ * This routine returns 0 iff the first character is one of 'Yy1Nn0', or
+ * 'Oo' when the second character is one of 'fFnN' (for "on" and "off").
  * Otherwise it will return -EINVAL.  Value pointed to by res is
  * updated upon finding a match.
  */
 int strtobool(const char *s, bool *res)
 {
+	if (!s)
+		return -EINVAL;
+
 	switch (s[0]) {
 	case 'y':
 	case 'Y':
@@ -652,6 +656,21 @@ int strtobool(const char *s, bool *res)
 	case '0':
 		*res = false;
 		break;
+	case 'o':
+	case 'O':
+		switch (s[1]) {
+		case 'n':
+		case 'N':
+			*res = true;
+			break;
+		case 'f':
+		case 'F':
+			*res = false;
+			break;
+		default:
+			return -EINVAL;
+		}
+		break;
 	default:
 		return -EINVAL;
 	}
-- 
1.9.1